Invasive Species: Yellow Flag Iris

Iris Pseudacorus

Yellow flag iris is a popular ornamental that escapes and impacts riparian areas.

Why is it important to control?

Irrigation canals and flood control ditches can be severely restricted. Riparian area diversity is impacted as well.

Image of flowering yellow flag iris at the water's edge

How can you identify it?

Close up image of a yellow flag iris flowerImage of yellow flag iris seeds about to drop
Habitat: Moist soil areas and shallow water.
Life Cycle: Perennial
Height: Up to 4 feet
Leaf Description: Long, flattened and sword-like.
Fruit & Flower Description: Showy yellow flowers on erect plant stalks. Fruit capsules up to 4 inches in length. Brown, flattened seeds that float.
Bloom Time: April to June

How do you control it?

  • Dig out individual plants and small clumps.

  • For larger patches, consider covering with black tarps to kill the plants.

  • Oregon State University has herbicide control methods. FOLLOW ALL LABEL DIRECTIONS!

  • The Oregon Department of Agriculture has not identified any biocontrols.

How to Report it?

There are various ways you can report this noxious weed.

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